The present invention relates to a pumping appartus for feeding solution to a reverse osmosis unit and more particularly to such pumping apparatus which provides for the recovery of pumping energy.
It has previously been proposed to recover some proportion of the pumping energy required in feeding a reverse osmosis unit, one such proposal being described in U.S. Pat. No. 4,354,939 issued Oct. 19, 1982 to Curt M. Pohl. A similar proposal is described in the article entitled "Energy Recovery for Small Reverse Osmosis Systems" by Jeffery C. Ide and Melvin E. Matson. A small, manually operated, reverse osmosis apparatus incorporating some energy recovery is described in U.S. Pat. No. 4,187,173 to Bowie G. Keefer.
While these prior art proposals show the desirablity of recovering pumping energy which is otherwise lost in the discharge flow of concentrate, the systems have not found general acceptance due to the difficulty of implementation. Typically these systems have involved multiple pumps operating on sea water and/or brine at high pressure. As is understood by those skilled in the art, pumps suitable for such application are not readily available and the application conditions essentially define a hostile environment for such machinery.
Among the several objects of the present invention may be noted the provision of novel pumping apparatus for a reverse osmosis unit which will efficiently recover pumping energy from the concentrate discharge flow; the provision of such a pumping system which does not require the pumping of solution or concentrate at high pressures; the provision of such apparatus which can be constucted using relatively conventional components; the provision of such a system which requires a minimal number of pumps; the provision of such a system which is highly efficient; the provision of such a system which is highly reliable and the provision of such a system which is of relatively simple and inexpensive construction. Other objects and features will be in part apparent and in part pointed out hereinafter.